Options for fanless PCI-e video card

im looking for a video card that will work well with mythtv. i currently have a 7300GT. im very pleased with its performance, but the fan is quite loud and im looking for a fanless solution.

Needs:
Fanless
PCI express x16
low power consumption (equal or lower than 7300GT with comparable performance)
low heat (in a small form factor case. only fans are the CPU and PSU. its a BTX board so the cpu fan blows on the vid card too)
you can see the case layout here (big pic!) http://hondaswap.com/gallery/data/500/riley_077.jpg

im kind of at odds with myself. on one hand i want to go with a lower performance card for lower heat and lower price. (cant seen to find an fx5200 in pci-e and fanless) and on the other hand i might want a better performing one at the cost of more heat and price because i may want to do some games (NES/SNES/N64/PSX emulation). do i NEED a better vid card for this? or can the 3D stuff be done in the CPU? like how you can avoid XvMC with a better vid card. also lately ive been focusing on vid cards that are 128-bit. how much difference does it make in a mythtv setup over a 64-bit memory interface?

oh and keep in mind that this case uses a riser card and the back of the video card sits nearly flush with the top of the case. this prevents me from using any video card in which the heat sink wraps around to the back of the card. like the asus 7300GT

they are a lot of fanless variants of the nvidia 8000 series line up all the way to the 8800gt i believe. probably looking at either an 8500gt or 8600gt. better yet, there is the 7600gs. its a little faster than the 7300gt and i image the power draw to be about equal. i had the evga 7600gs passive and liked it. roughly the speed of the 6600gt but a bit faster and a lot less noise =). i think u can find one for like $40-50. but if u want to go with a little less power, the 8400gs is great too, plus it has hardware hd decoding! ive seen them go for like 30-40 after rebate.

and for emulator, its much more cpu than video. its noted in some of their release notes for like mame and stuff.

id stick with 128bit because the extra bandwidth would probably benefit the heavy video streaming, especially if it was hd content and the price is pretty much moot.

hardware HD doesnt really sell for me. im using it on mythtv, which as you may know is linux. and hardware HD decoding isnt supported in the driver yet. if ever. thats why im kind of learning away from the 8000 series. i just have a feeling that it will pull more power and i think im on the edge as it is lol. only have a 275W PSU. if i ever need to do HD content on this frontend, ill just get a better CPU and sick with the cheap video card.

Sapphire has a passively cooled 8800GT. Beyond that, you might want to look into some of the aftermarket coolers. I don't remember who makes the good aftermarket coolers for the 8800, but most of them involve a block with heat pipes going to a large set of fins on the back side of the card.

Or you could go water cooled like me. Except mine's FAR from silent! Well, the HTPC is silent.

low power consumption mike... lol. 275W PSU is what im working with. i fear anything more powerful than the 7300GT that i have may be too much. since im not using much GPU in my system i just need something lightweight that can handle HD in the future (not necessarily processsing it, but displaying it, as a CPU upgrade can deal with HD processing)

the new backend im working on will not be silent but itll be pretty damn quiet:

Oh, ok- get one of the non-overclocked versions of the 8600GT. That way you're still on the 8000 series architecture, and the non-OC versions don't take any extra power beyond what's available in the PCI-E slot (75W or less). You can get 8600GTs without fans too. GT, not GTS.

By the way- I measured the power consumption of my Q6600. At idle, my system eats 240W from the wall, and at full tilt (CPU only) it ate 308W. The Q6600 is quite efficient! Take into account a 75% power supply efficiency and you have a difference of only 51W from idle to full power.